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  • Muscle & IGF Research
  • IGF-1 LR3

    • IGF-1 LR3

    IGF-1 LR3, 83-amino acid extended IGF-1 analogue with an Arg3 substitution that sharply reduces IGF-binding-protein binding, raising potency over IGF-1 in cell systems that secrete those proteins.

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    IGF-1 LR3

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    Buy the 10-pack - save 66%/mg. Single vials welcome — checkout needs 5+ vials or any 10-vial pack - build a custom vial pack

    Lab-direct quality — full packs or single-vial samples

    Every batch ships straight from the lab that synthesises it — sealed, tamper-evident, and verified to >99% HPLC purity . Buying direct means you pay the lab-direct rate on every vial, with nothing stacked on top.

    Order a sealed 10-vial research pack , or add a single-vial laboratory sample alongside your pack to evaluate a compound at smaller scale first. Same lab, same batch, same verified purity — scaled to whatever your research needs.

    What It's Researched For

    In plain terms, IGF-1 LR3 is studied mainly as a muscle-growth and cell-growth research compound. Here is what that looks like across the research.

    Muscle growth & new muscle cells

    Research explores how it switches on muscle stem cells and the formation of new muscle cells.

    Protein building & repair

    Studied for ramping up the protein-synthesis machinery that muscle and connective tissue use to rebuild.

    Lab cell-growth standard

    Widely used as a standard growth factor to keep cultured cells alive and multiplying in cell-culture and bioprocessing research.

    Nutrient & glucose uptake

    Research looks at how it helps cells take up glucose and amino acids, overlapping with insulin signalling.

    Long-acting IGF-1 model

    Used as a long-lasting version of natural IGF-1 to study its signalling without it being mopped up in the bloodstream.

    Overview

    In short: IGF-1 LR3 (Long Arginine 3 IGF-1) is an 83-amino-acid recombinant IGF-1 analog engineered to escape IGF-binding protein sequestration, which raises its potency over native IGF-1 in cell systems that secrete those proteins.

    Key research facts

  • Arg3 substitution eliminates IGFBP binding increasing free bioavailable IGF-1 approximately 3-fold
  • 13-amino acid N-terminal extension and Arg3 substitution reduce binding to IGF-binding proteins
  • Full IGF-1R agonist activating PI3K/Akt/mTOR protein synthesis and RAS/RAF/MEK/ERK proliferation pathways
  • Bypasses hepatic GH/JAK2/STAT5 axis, direct peripheral tissue receptor activation
  • Promotes hyperplasia (new muscle cell formation) and mitogenesis via satellite cell activation

    • These points summarise lab themes, not human outcomes.

    IGF-1 (insulin-like growth factor 1) is the hormone that does most of the downstream anabolic work when growth hormone is around. Problem: in the bloodstream, roughly 98% of native IGF-1 is bound up by a family of six IGF-binding proteins (IGFBPs) that act as a buffer, keeping the free, active fraction tiny.

    IGF-1 LR3 is an engineered version designed to defeat that buffer. It has two modifications: a 13-amino-acid N-terminal extension (MFPAMPLSSLFVN) and a single amino acid substitution that replaces glutamate at position 3 with arginine. Together, those changes virtually eliminate IGFBP binding, leaving the peptide free and active in circulation.

    The practical consequence is higher potency than native IGF-1 in cell systems that secrete IGF-binding proteins (roughly 1.5- to 6-fold in rats, depending on the study and endpoint), although the analogue is cleared from the circulation more quickly than IGF-1. IGF-1 LR3 is widely used in cell culture, bioprocessing, and muscle/performance research. Supplied here as sterile lyophilised powder.

    Mechanism of Action

    IGF-1 LR3 activates the IGF-1 receptor directly - driving protein synthesis, cell proliferation, and glucose uptake - without getting trapped by circulating IGF-binding proteins.

    Pathway Effect Why it matters IGF-1 receptor (IGF-1R) Full tyrosine kinase receptor activation Same downstream pharmacology as native IGF-1 but with far higher free fraction PI3K / Akt / mTOR Drives protein synthesis and cell survival Core anabolic signalling cascade for muscle and connective tissue RAS / RAF / MEK / ERK Cellular proliferation and differentiation Supports hyperplasia - new cell formation - in muscle satellite cells N-terminal extension 13-residue MFPAMPLSSLFVN prefix Disrupts IGFBP binding and stabilises the peptide in circulation Arg3 substitution Arginine replaces native glutamate at position 3 Finishes the job of eliminating IGFBP sequestration Deeper dive for scientific readers

    Francis et al. (Journal of Molecular Endocrinology, 1992) described the LR3 analog: in cell lines that secrete IGF-binding proteins the N-terminal analogues were more potent than native IGF-1, which the authors attributed to reduced IGFBP interaction, while in a cell line with no detectable secreted IGFBPs Long [Arg3]-IGF-I was less potent than IGF-1. In rats LR3 IGF-I is cleared from the circulation more quickly than IGF-I (Tomas et al., J Endocrinol 1996), and no published human pharmacokinetic study was found. Originally developed by CSIRO Australia and commercialised by Repligen under the LONG R3 IGF-I trademark for cell culture and bioprocessing applications. Banned by WADA for competing athletes.

    Common Questions People Are Asking

    What is IGF-1 LR3?

    IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is an 83-amino-acid analogue of human IGF-1 with an N-terminal extension and an Arg substitution at position 3. Those modifications greatly reduce its binding to IGF-binding proteins, which raises its potency over native IGF-1 in cell systems that secrete those proteins. It is supplied as a lyophilised research-grade powder for laboratory use only.

    What does IGF-1 LR3 do?

    In research models IGF-1 LR3 activates the IGF-1 receptor (and PI3K/Akt and MAPK signalling) to drive cell growth, proliferation, differentiation and survival - with a much longer duration of action than native IGF-1 because it evades IGFBP sequestration. These are findings in cell and animal models; New-U supplies it for laboratory research only and implies no human effect.

    What is IGF-1 LR3 used for?

    IGF-1 LR3 is widely used as a cell-culture supplement to support proliferation and survival of cultured cells, and as a research tool for studying IGF-1-receptor signalling, hypertrophy and tissue-growth endpoints. New-U supplies it strictly for in-vitro and laboratory research.

    Does IGF-1 LR3 show up on a drug test?

    Standard employment or clinical drug panels (including typical LabCorp steroid panels) do not screen for IGF-1 LR3 - it is a peptide, not a small-molecule steroid, and requires specialised assays. It is, however, on the WADA Prohibited List, and anti-doping authorities use dedicated tests for IGF-1 analogues.

    What does "LR3" actually mean?

    "L" for the 13-amino-acid N-terminal extension (MFPAMPLSSLFVN), "R" for arginine, and "3" for position 3 of the IGF-1 sequence. So "LR3" literally means "the Long variant with an Arginine at position 3". Together the two modifications greatly reduce IGFBP binding.

    How is IGF-1 LR3 different from IGF-1 DES?

    IGF-1 DES is the opposite end of the design spectrum - a truncated 67-residue form missing the N-terminal tripeptide GPE, which also dramatically reduces IGFBP binding. IGF-1 LR3 uses a 13-residue extension to achieve similar IGFBP resistance. Both are more potent than native IGF-1 in cell systems that secrete binding proteins (Francis et al., 1992); they differ in structure and in how they were designed.

    Why is IGF-1 LR3 used in cell culture?

    Native IGF-1 is inefficient in cell culture because IGFBPs produced by the cells themselves can sequester it, reducing effective concentrations. IGF-1 LR3 escapes that sequestration and delivers consistent, reproducible growth-factor signalling. That is why it is an industry standard for bioprocessing and mammalian cell culture.

    How should IGF-1 LR3 be stored?

    Keep the lyophilised powder frozen at −20 °C (−80 °C for long-term storage). After reconstitution, refrigerate at 1-6 °C and protect from light. IGF-1 LR3 is a structured protein and is sensitive to repeated freeze-thaw cycles - aliquot if you need multiple aliquots from one reconstitution.

    How is IGF-1 LR3 reconstituted in the lab?

    Because IGF-1 LR3 is a structured protein that tends to aggregate in neutral aqueous solution, laboratory practice commonly reconstitutes it in dilute acetic acid (around 0.1%, ~10 mM) rather than plain water, which keeps it in a non-aggregated state; bacteriostatic or sterile water is also used. The vial is allowed to reach room temperature before opening to avoid condensation, then gently rolled rather than shaken. This is general handling guidance for research material, not a dosing instruction.

    Where can I buy IGF-1 LR3?

    Right here - IGF-1 LR3 is supplied directly by New-U Research Compounds on this page. Every batch is independently third-party tested to >99% HPLC purity with a batch-linked Certificate of Analysis, supplied as lyophilised research-grade material, and shipped direct from source worldwide in discreet, tracked packaging.

    How much does IGF-1 LR3 cost?

    IGF-1 LR3 pricing is shown live on this page, per pack size - 10-vial research packs as standard, with single-vial sample options on selected compounds. Larger vial strengths lower the per-mg cost, the batch Certificate of Analysis is published on this page, and shipping is free on orders over $350.

    Is IGF-1 LR3 third-party tested?

    Yes. Every IGF-1 LR3 batch is verified by independent laboratories (Janoshik Analytics and Freedom Diagnostics) for identity and purity, with a batch-linked Certificate of Analysis confirming >99% HPLC purity. Current batch certificates are published on this page and on our COA page rather than packed with orders.

    How do I buy IGF-1 LR3?

    Add the IGF-1 LR3 pack size you need to your cart and check out: enter your shipping details, then choose your payment method - cryptocurrency or card - on the next step. The batch Certificate of Analysis (COA) is published on this page, so you can check it before you order.

    What payment methods can I use to buy IGF-1 LR3?

    At checkout you can pay by card or crypto. New-U supports BTC and selected stablecoin and network-asset payments across Ethereum, Solana, TRON, Polygon, Base, BNB Chain and Linea. You choose your method after confirming your order.

    How fast is shipping, and do you ship worldwide?

    Yes - we ship worldwide in discreet, unmarked, tracked packaging; lyophilised peptides are stable through the tracked transit window. Delivery typically takes 6–14 business days, and shipping is free on orders over $350.

    Is it legal to buy IGF-1 LR3?

    In the United States, IGF-1 LR3 is sold strictly for laboratory and research purposes only. It is not approved by the FDA for human consumption and is not sold for that purpose. Regulatory status varies by jurisdiction - buyers are responsible for compliance in their own region.

    Research use only - all claims made on this site are for testing and research use only.

    Pharmacokinetics

    Stability Lyophilised powder: store in freezer (−20 °C). Reconstituted: refrigerate 1–6 °C, away from sunlight. Use within the validated stability window for the specific batch and formulation. Notes Very low IGF-binding-protein affinity; in rats LR3 IGF-I was cleared from the circulation more quickly than IGF-I (Tomas et al., J Endocrinol 1996) and no published human pharmacokinetic study was found; produced via recombinant E. coli expression with chromatographic purification and refolding. Not FDA-approved, mecasermin (native rhIGF-1) is approved for pediatric primary IGFD. Banned by WADA.

    Evidence Tier

    Overall: Tier 2: Animal / preclinical

    IGF-1 LR3 has robust mammalian in-vivo characterisation (pigs, marmoset monkeys, DMD models) and is an industry-standard in-vitro cell-culture growth factor, but there are no human clinical trials of the LR3 analogue itself. The native molecule mecasermin (rhIGF-1) is FDA-approved for paediatric primary IGF-1 deficiency, whereas LR3 specifically is unapproved research-only material and is on the WADA Prohibited List.

    Tier 2 · Animal

  • Francis et al. (J Mol Endocrinol, 1992) - characterisation of the LR3 analogue; more potent than IGF-1 in IGFBP-secreting cell lines through reduced IGFBP interaction
  • IGF-I analogues that bind IGFBPs poorly showed more potent, prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys (J Endocrinol, 1997; PMID 9415072)
  • Superior injected potency of poorly-IGFBP-bound IGF-I analogues (J Endocrinol, 1996; PMID 8708565)

    • Certificates, databases & peer-reviewed sources

    Last reviewed: 16 June 2026 · New-U Research Compounds

  • Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection. Journal of Endocrinology. · 1996 · PMID: 8708565 · DOI: 10.1677/joe.0.1500077
  • IGF-I variants which bind poorly to IGF-binding proteins show more potent and prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys. Journal of Endocrinology. · 1997 · PMID: 9415072 · DOI: 10.1677/joe.0.1550377
  • PubMed: peer-reviewed literature on IGF-1 LR3
  • ClinicalTrials.gov: registered studies on IGF-1 LR3
  • IGF-1 LR3: Wikipedia
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    • Key Characteristics

  • Recombinant 83-amino-acid IGF-1 analog
  • N-terminal 13-residue extension + Arg3 substitution
  • Sharply reduced binding to IGF-binding proteins
  • Cleared from the circulation faster than IGF-1 in rats
  • Higher potency than IGF-1 in IGFBP-secreting cell systems
  • Standard cell culture and bioprocessing growth factor
  • WADA-prohibited for competing athletes
  • Research-grade purity: >99% HPLC

    • Specifications

    Molecular Formula Recombinant 83-aa peptide Molecular Weight 9117.5 Da Length 83 amino acids (IGF-1 70-aa + 13-aa N-terminal extension) Purity >99% (HPLC) Form Lyophilised powder (E. coli recombinant) Half-life Not established in humans; cleared faster than IGF-1 in rats IGFBP binding Very low affinity for IGF-binding proteins Route Subcutaneous or intramuscular injection Storage Lyophilised: −20 °C freezer. Reconstituted: 1-6 °C, away from light.

    About IGF-1 LR3 (Long R3 IGF-1): IGF-1 Signalling & Cell-Culture Research Guide

    IGF-1 LR3 was originally engineered for the cell culture and bioprocessing industry rather than for medicine. The fundamental problem it solves is that native IGF-1 has a free-fraction problem: most of the peptide in circulation is sequestered by IGF-binding proteins (IGFBPs), so useful concentrations require high doses. Adding a 13-residue N-terminal extension (MFPAMPLSSLFVN) and swapping glutamate for arginine at position 3 greatly reduces the IGFBP interaction and leaves the peptide free and active in cell systems that secrete binding proteins - the basis for its higher potency over native IGF-1 there. In rats it is cleared from the circulation more quickly than IGF-1, so a longer half-life should not be assumed.

    Repligen commercialised the modified peptide under the LONG R3 IGF-I trademark, and it became an industry-standard growth factor for mammalian cell culture. Researchers studying muscle growth, satellite-cell activation, recovery, and connective-tissue repair then picked it up as a tool compound for studying IGF-1-receptor (PI3K/Akt/mTOR and RAS/RAF/MEK/ERK) pharmacology without the complication of the IGFBP buffer.

    New-U Research Compounds supplies IGF-1 LR3 as a recombinant lyophilised powder at >99% HPLC purity, verified by independent third-party labs. All material is strictly for in-vitro and laboratory research. IGF-1 LR3 is structured protein material that is sensitive to repeated freeze-thaw cycles, so it is typically reconstituted in dilute acetic acid to limit aggregation and then aliquoted. It is not approved for human therapeutic use (mecasermin, the native rhIGF-1, is the approved drug for paediatric primary IGF deficiency) and is on the WADA Prohibited List. Nothing on this page is medical advice or a dose recommendation.

  • IGF-1 LR3 - Wikipedia
  • Insulin-like growth factor 1 - Wikipedia
  • Insulin-like growth factor 1 receptor - Wikipedia
  • Mecasermin - Wikipedia

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    • IGF-1 LR3 vs related Muscle / Performance compounds

    Compound Price Purity spec COA IGF-1 LR3 from $104 >99% HPLC On request PEG-MGF from $172 >99% HPLC On request IGF-DES from $146 >98% HPLC On request

    Descriptive catalog comparison for research sourcing decisions - not dosing guidance.

    More on IGF-1 LR3

  • Muscle & IGF Research research compounds
  • IGF-1 LR3 research guide
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    • Research this compound

  • Research guide IGF-1 LR3 research guide IGF-1 LR3 activates the IGF-1 receptor directly - driving protein synthesis, cell proliferation, and glucose uptake - without getting… Read the guide →
  • Related research IGF-1 LR3 Explained: Why a Modified Analogue Behaves Differently From IGF-1 An 83-amino-acid IGF-1 analogue whose extra potency in cells comes from escaping IGF-binding proteins, not from a stronger receptor signal… Read the article →

    • Part of the Tissue repair & recovery research research area — explore related compounds, guides and sources.

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    [image: IGF-1 LR3 research vial — Muscle / Performance compound supplied by New-U Research Compounds]

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